[gonyea]

It's a lot of things. "Product Developer" captures it quite well. You're going from 0 to ShipIt with minimal bottlenecks.

"Isn't that just an architect?" Except you're not a silo'd backseat driver–ahem! Architecture Review Committee Member–meddling with various teams.

"UX guy?" No, you're building the API, deploying the infrastructure, setting up the DB, and then consuming all of that on the front-end.

"A full-stack developer?" Except full-stack developers are usually weighted heavily to one side, or they get pigeon-holed on Day 1 wherever the team is lacking (usually Ops. Sigh).

But "Sr. Actually-Full-Stack Developer" would be an alternate job title to "Product Developer." You need a lot of discipline (and experience) to not over-engineer a new product to death.